The popularity enjoyed by hi-fidelity sound reproduction equipment over the last few decades has spawned development of various accessories to be used in conjunction with listening to music. One popular species of these accessories has been a sound-responsive light display commonly known as a "light organ".
In most conventional light organs an audio input signal is divided into two or more discrete frequency bands by electronic filters. The output of these filters is proportional to the energy within the filter's bandwidth in the sound field. The outputs of the filters are used to turn on light-emitting elements of different colors; there usually being a separate color for each band. A common arrangement has been to intensity modulate each light according to the output level from the filter driving the light.
While this type of device has enjoyed some popularity, the visible output from such devices tends to be very repetitious, particularly in response to certain types of music such as loud rock music. For example, the light-emitting element connected to the filter responsive to the lowest range of frequencies tends to pulsate to some degree while the other lights remain lit at a more or less constant intensity. One previous system proposed to overcome this phenomenon, which was characterized as a "threshold problem", using a modified differentiation circuit to render the individual lights responsive to changes, rather than absolute value, in intensity within each band covered by a filter. While it is believed that this has led to some improvement, there is still very little variety in the overall impression made by the visible output to be derived from such devices.
Other light-emitting decorative or entertainment devices have included articles of personal jewelry with an array of LEDs sequentially lit in a sequence determined by pseudo random number generators. One such system proposed switching from a first array of LEDs having a first set of colors to a second array of LEDs having another set of colors in response to the intensity of a local sound field detected by a microphone.
Heretofore no prior art light organ arrangement has provided a simple, inexpensive, sound actuated light display which is readily and selectively adjustable to provide visible display outputs of widely differing characteristics in the same device.
While the characterization of the output of a light organ as interesting or boring is highly subjective, it is believed by the inventor of the present invention that increasing the variety of possible patterns in the visible display, and the ability to selectively create styles of patterns by adjustments of front panel control knobs, each of which dynamically changes in response to the intensity of a sound field, provides a much more interesting visible output. This variety will hold the attention of the user for a greater length of time than conventional light organs.